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[PATCH v2 6/9] block/io: expand in_flight inc/dec section: block-status
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
[PATCH v2 6/9] block/io: expand in_flight inc/dec section: block-status |
Date: |
Mon, 27 Apr 2020 17:39:04 +0300 |
It's safer to expand in_flight request to start before enter to
coroutine in synchronous wrappers and end after BDRV_POLL_WHILE loop.
Note that qemu_coroutine_enter may only schedule the coroutine in some
circumstances.
block-status requests are complex, they involve querying different
block driver states across backing chain. Let's expand only in_flight
section for the top bs, keeping other sections as is.
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
block/io.c | 65 ++++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 51 insertions(+), 14 deletions(-)
diff --git a/block/io.c b/block/io.c
index a91d8c1e21..1cb6f433e5 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2303,6 +2303,10 @@ int coroutine_fn
bdrv_co_block_status_from_backing(BlockDriverState *bs,
* _ZERO where possible; otherwise, the result favors larger 'pnum',
* with a focus on accurate BDRV_BLOCK_ALLOCATED.
*
+ * If 'inc_in_flight' is true, in_flight counter will be increased for bs
during
+ * the operation. All nested block_status calls will increase the counter for
+ * corresponding bs anyway.
+ *
* If 'offset' is beyond the end of the disk image the return value is
* BDRV_BLOCK_EOF and 'pnum' is set to 0.
*
@@ -2321,7 +2325,7 @@ int coroutine_fn
bdrv_co_block_status_from_backing(BlockDriverState *bs,
* set to the host mapping and BDS corresponding to the guest offset.
*/
static int coroutine_fn bdrv_co_block_status(BlockDriverState *bs,
- bool want_zero,
+ bool want_zero, bool
inc_in_flight,
int64_t offset, int64_t bytes,
int64_t *pnum, int64_t *map,
BlockDriverState **file)
@@ -2372,7 +2376,9 @@ static int coroutine_fn
bdrv_co_block_status(BlockDriverState *bs,
goto early_out;
}
- bdrv_inc_in_flight(bs);
+ if (inc_in_flight) {
+ bdrv_inc_in_flight(bs);
+ }
/* Round out to request_alignment boundaries */
align = bs->bl.request_alignment;
@@ -2409,7 +2415,7 @@ static int coroutine_fn
bdrv_co_block_status(BlockDriverState *bs,
if (ret & BDRV_BLOCK_RAW) {
assert(ret & BDRV_BLOCK_OFFSET_VALID && local_file);
- ret = bdrv_co_block_status(local_file, want_zero, local_map,
+ ret = bdrv_co_block_status(local_file, want_zero, true, local_map,
*pnum, pnum, &local_map, &local_file);
goto out;
}
@@ -2436,7 +2442,7 @@ static int coroutine_fn
bdrv_co_block_status(BlockDriverState *bs,
int64_t file_pnum;
int ret2;
- ret2 = bdrv_co_block_status(local_file, want_zero, local_map,
+ ret2 = bdrv_co_block_status(local_file, want_zero, true, local_map,
*pnum, &file_pnum, NULL, NULL);
if (ret2 >= 0) {
/* Ignore errors. This is just providing extra information, it
@@ -2459,7 +2465,9 @@ static int coroutine_fn
bdrv_co_block_status(BlockDriverState *bs,
}
out:
- bdrv_dec_in_flight(bs);
+ if (inc_in_flight) {
+ bdrv_dec_in_flight(bs);
+ }
if (ret >= 0 && offset + *pnum == total_size) {
ret |= BDRV_BLOCK_EOF;
}
@@ -2473,9 +2481,15 @@ early_out:
return ret;
}
+/*
+ * If 'inc_in_flight' is true, in_flight counter will be increased for bs
during
+ * the operation. All block_status calls to the backing chain of bs will
+ * increase the counter for corresponding bs anyway.
+ */
static int coroutine_fn bdrv_co_block_status_above(BlockDriverState *bs,
BlockDriverState *base,
bool want_zero,
+ bool inc_in_flight,
int64_t offset,
int64_t bytes,
int64_t *pnum,
@@ -2488,11 +2502,13 @@ static int coroutine_fn
bdrv_co_block_status_above(BlockDriverState *bs,
assert(bs != base);
for (p = bs; p != base; p = backing_bs(p)) {
- ret = bdrv_co_block_status(p, want_zero, offset, bytes, pnum, map,
- file);
+ ret = bdrv_co_block_status(p, want_zero, inc_in_flight,
+ offset, bytes, pnum, map, file);
if (ret < 0) {
break;
}
+ inc_in_flight = true;
+
if (ret & BDRV_BLOCK_ZERO && ret & BDRV_BLOCK_EOF && !first) {
/*
* Reading beyond the end of the file continues to read
@@ -2514,15 +2530,16 @@ static int coroutine_fn
bdrv_co_block_status_above(BlockDriverState *bs,
}
static int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs,
+ bool inc_in_flight,
int64_t offset, int64_t bytes,
int64_t *pnum)
{
int ret;
int64_t dummy;
- ret = bdrv_co_block_status_above(bs, backing_bs(bs), false, offset,
- bytes, pnum ? pnum : &dummy, NULL,
- NULL);
+ ret = bdrv_co_block_status_above(bs, backing_bs(bs), false, inc_in_flight,
+ offset, bytes, pnum ? pnum : &dummy,
+ NULL, NULL);
if (ret < 0) {
return ret;
}
@@ -2535,7 +2552,7 @@ static void coroutine_fn
bdrv_block_status_above_co_entry(void *opaque)
BdrvCoBlockStatusData *data = opaque;
data->ret = bdrv_co_block_status_above(data->bs, data->base,
- data->want_zero,
+ data->want_zero, false,
data->offset, data->bytes,
data->pnum, data->map, data->file);
data->done = true;
@@ -2567,6 +2584,8 @@ static int
bdrv_common_block_status_above(BlockDriverState *bs,
.done = false,
};
+ bdrv_inc_in_flight(bs);
+
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_block_status_above_co_entry(&data);
@@ -2575,6 +2594,9 @@ static int
bdrv_common_block_status_above(BlockDriverState *bs,
bdrv_coroutine_enter(bs, co);
BDRV_POLL_WHILE(bs, !data.done);
}
+
+ bdrv_dec_in_flight(bs);
+
return data.ret;
}
@@ -2624,15 +2646,19 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState
*bs, int64_t offset,
* words, the result is not necessarily the maximum possible range);
* but 'pnum' will only be 0 when end of file is reached.
*
+ * To be called between exactly one pair of bdrv_inc/dec_in_flight() for top
bs.
+ * bdrv_do_is_allocated_above takes care of increasing in_fligth for other
block
+ * driver states from bs backing chain.
*/
static int coroutine_fn
-bdrv_co_is_allocated_above(BlockDriverState *top, BlockDriverState *base,
+bdrv_do_is_allocated_above(BlockDriverState *top, BlockDriverState *base,
bool include_base, int64_t offset, int64_t bytes,
int64_t *pnum)
{
BlockDriverState *intermediate;
int ret;
int64_t n = bytes;
+ bool inc_in_flight = false;
assert(base || !include_base);
@@ -2642,10 +2668,12 @@ bdrv_co_is_allocated_above(BlockDriverState *top,
BlockDriverState *base,
int64_t size_inter;
assert(intermediate);
- ret = bdrv_co_is_allocated(intermediate, offset, bytes, &pnum_inter);
+ ret = bdrv_co_is_allocated(intermediate, inc_in_flight, offset, bytes,
+ &pnum_inter);
if (ret < 0) {
return ret;
}
+ inc_in_flight = true;
if (ret) {
*pnum = pnum_inter;
return 1;
@@ -2682,11 +2710,16 @@ typedef struct BdrvCoIsAllocatedAboveData {
bool done;
} BdrvCoIsAllocatedAboveData;
+/*
+ * To be called between exactly one pair of bdrv_inc/dec_in_flight() for top
bs.
+ * bdrv_do_is_allocated_above takes care of increasing in_fligth for other
block
+ * driver states from the backing chain.
+ */
static void coroutine_fn bdrv_is_allocated_above_co_entry(void *opaque)
{
BdrvCoIsAllocatedAboveData *data = opaque;
- data->ret = bdrv_co_is_allocated_above(data->top, data->base,
+ data->ret = bdrv_do_is_allocated_above(data->top, data->base,
data->include_base,
data->offset, data->bytes,
data->pnum);
@@ -2709,6 +2742,8 @@ int bdrv_is_allocated_above(BlockDriverState *top,
BlockDriverState *base,
.done = false,
};
+ bdrv_inc_in_flight(top);
+
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_is_allocated_above_co_entry(&data);
@@ -2718,6 +2753,8 @@ int bdrv_is_allocated_above(BlockDriverState *top,
BlockDriverState *base,
BDRV_POLL_WHILE(top, !data.done);
}
+ bdrv_inc_in_flight(top);
+
return data.ret;
}
--
2.21.0
- [PATCH v2 0/9] block/io: safer inc/dec in_flight sections, Vladimir Sementsov-Ogievskiy, 2020/04/27
- [PATCH v2 1/9] block/io: refactor bdrv_is_allocated_above to run only one coroutine, Vladimir Sementsov-Ogievskiy, 2020/04/27
- [PATCH v2 3/9] block/io: move flush and pdiscard stuff down, Vladimir Sementsov-Ogievskiy, 2020/04/27
- [PATCH v2 4/9] block/io: move bdrv_rw_co_entry and friends down, Vladimir Sementsov-Ogievskiy, 2020/04/27
- [PATCH v2 6/9] block/io: expand in_flight inc/dec section: block-status,
Vladimir Sementsov-Ogievskiy <=
- [PATCH v2 7/9] block/io: add bdrv_do_pwrite_zeroes, Vladimir Sementsov-Ogievskiy, 2020/04/27
- [PATCH v2 8/9] block/io: move bdrv_make_zero under block-status, Vladimir Sementsov-Ogievskiy, 2020/04/27
- [PATCH v2 2/9] block/io: refactor bdrv_co_ioctl: move aio stuff to corresponding block, Vladimir Sementsov-Ogievskiy, 2020/04/27
- [PATCH v2 5/9] block/io: expand in_flight inc/dec section: simple cases, Vladimir Sementsov-Ogievskiy, 2020/04/27
- [PATCH v2 9/9] block/io: expand in_flight inc/dec section: bdrv_make_zero, Vladimir Sementsov-Ogievskiy, 2020/04/27